Electric heating unit.



H. P. BALL.

ELBGTRIG HEATING UNIT.

APPLIGATION FILED APE. 2s, 191s.

Patented Dec. 22, 1914.

Witneses:

lhvento: Herwig Price Bed I, @d

M., Hsaflttorwe ing tively resist rough UNITED STATES MASSACHUSETTS, ASSIGNOR TO GENERAL NEW YORK.

ELECTRIC HEATING UNIT.

Specification of Letters Patent.

Patented Dec. 22, 1914.

Application filed April 23, 1913. Serial No. 763,015.

To czZZ Lv/1.0m t may conce/m Be it known that I, HENRY PRICE BALL, a citizen of the United States, residing at Pittsfield, county of Berkshire, State of lvfassachusetts, have invented certain new andY useful Improvements in Electric Heating Units, of which the following is a specification.

My invention relates to fiat electric resistance heating units such as are suitable for use independently as stoves or as parts of heating devices of various kinds.

'Ihe object of my invention is to produce a device of this character which will effechandling and which will not be injuriously affected by the high temperature to which it is subjected in use.

According to my invention I utilize as the resistance element of the device a wire which consists of an inner conductor, an outer metal sheath and insulating material therebetween. Such wire is commonly termed metal sheathed wire. I use one or more coils of metal sheathed wire to constitute the outer or peripheral portion of the heating unit. If more than one coil is used, I prefer to unite metal spacers to each of the coils in such a way as to form a flat upper surface. The center portion of the unit consists of a metal plate which is united to the sheath wire so as to form an integral device. The construction is such that the metal plate and the surrounding heating elements are located in substantially the same plane. It will be readily seen that such a structure will be very rugged and withstand considerable rough usage. It will also be apparent that, as the resistance element is located at the periphery of the unit, the expansion due to rise in temperature will be in such a direction as to tend to stretch the center plate and. as the said plate and the resistance element are located in substantially the same plane, this will not cause the plate to warp. The result is that by means of my invention a heating unit is secured which will retain ils .shape indefinitely.

My invention also includes improved terminals for the sheathed wire elements formpart of my improved unit. As the sheathed wire is disposed in a horizontal plane and it is necessary that the terminals be disposed below this plane in order that a convenient connection may be made with the external circuit, the sheathed wire must be bent. In the absence of means such as that provided by my invention for protecting the bent portions, the sheathed wire would soon be broken or burnt away at these points. According to my invention I provide a terminal box into which the sheathed wires project and in whichy they are bent at right angles. The box is filled with a granular insulation and a suitable cover provided which is compressed tightly against the said insulation. Suitable terminal pins may bebrazed to the ends of the sheathed wires so they project through the boX cover.

My invention will be more clearly understood by referring to the accompanying drawing, in which* igure 1 is a top plan view bodying my invention in the struction; F ig. 2 is a central vertical section of the same; and F ig. 3 is a plan view on a reduced scale of the completed stove.

In constructing a stove such as that shown in the drawing, a plate of'copper or other metal having high heat conductivity having offset portions 11 and 12 has wound around the periphery a plurality of coils 13 of metallic sheath wire and intermediate spacers 14, the tops of the coils and the spacers being in the same plane as the top of the plate 10. These spacers are made of a material having good heat conductivityand may be of copper or steel and they are of such shape as to conform to the contiguous surfaces of the respective coils. If they are of steel they should carry layers of copper on such surfaces as are in contact with the sheathed wire. This metal sheathed wire may be of the kind well known to the art and comprising tor 15, an outer metallic sheath 16 and intermediate insulation 17 which may be material having a high dielectric strength such as boron nitrid which is disclosed in Pat-ent No. 1,063,483, which was issued to Ezechiel `Weintraub June 3, 1913. As shown in the drawing, there are two separate sections of the metal sheathed wire, one having the terminals 18, 19, and the other terminals 20, 21. 0n the bottom of the plate 10 and at the center of the same is provided a terminal box 9.2 which the ends 18, 19, 20 and 21 of the sheath wire enter. The top plate 23 of the said box is preferably brazed to the bottom of the plate. A layer of insulation of a stove emcourse of conan inner resistance conduc-l in substantially the same at right angles within the terminal box and each of the same enters the terminal pin 25 and is brazed to the same. The bra'zing mot-al may be aluminum bronze and the operation carried on in a reducing atmosphere to protect against oxidation.v rlhe brazing metal should be made to ill the spaces between the wire and the inside of the terminal pin. The terminal pins 25 are mounted in an insulating bushing 2.6. This may bej of sintered aluminum oxid disclosed in Patent No. 1,096,688, which was issued to Christian Dantsizen on May 12, 1914. Insulating material 27 is packed in the terminal box and is compressed compactly around the inner conductors of the sheathed wire by crimping over the sides 28 of the terminal box upon the bushing 26.

After the parts have been assembled as above described the spacers 14 may be brazed to the wire sheaths 17 by means of an Oxy-hydrogen flame. |The center plate 10 is also brazed to the metal sheath wire. The completed stove has the configuration shown in Fig. 3.

Owing to the fact that the coils of the metal sheathed wire are located in' substan- 'tially the same plane as the plate 10 and at the periphery of the same, when the said wire is-heated to a high temperature and the surrounding metal expands due to this high heat, the tension on the plate 10 will serve to preserve the same in a lat condition and prevent warpin or buckling. By means of the terminal ox arrangement the bending of the sheathed wire conductor is prevented, and this protects the same from being broken olf. The arrangement shown in the drawing permits three heats to be obtained by suitable combinations in series or parallel of the sections of sheathed wire by means of a three heat switch such as is well known in the art.

Various changes and modifications of the above described structure may be made without departing from the spirit of my invention and may be considered as coming within the scope of the annexed claims.

`What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. An electric resistance heating unit comprising a metal plate having a metal sheathed resistance element united to the periphery thereof and having its upper edge plane as the top of the plate. y

2. An electric resistance heating unit comprising a metal plate having a metal sheathed resistance wire bra-Zed to the periphery thereof and having its upper edge in substantially the same plane as the top of the plate.

of coils of metal sheathed wire disposed 1n 3. An electric resistance heating unit comprising a metal plate having a plurality of coils of metal sheathed wire united to the periphery thereof. and having its upper edge in substantially the same plane as the top of the plate.

4. An electric resistance heating unit comprising a metal plate having a plurality of coils of metal sheathed wire brazed to the periphery thereof and hav ing its upper edge in substantially the same plane as the top of the plate.

5. The combination of an electric resistance heating element comprising a plurality 8O the same plane and a terminal box throughV which the ends of the said wire pass and in which they are bent at right angles to the said plane containing insulating material compacted thereinaround the bends in the 35 said Wire.

6. The combination of an electric resistance element comprising an inner conductor, an outer sheath and insulating material compacted therebetween and a terminal box united tothe said outer sheath in which the said inner conductor is bent and having insulating material therein compacted around thebend in said inner conductor.

7. The combination of an electric resistance element comprising an inner conductor, an outer sheath and insulating material therebetween, and a terminal box into which the said inner conductor projects and in .which it is bent substantially at right angles having insulating material compacted therein around the bend in the said inner conductor.

8. The combination of an electric resistance element comprising an inner conductor, an outer sheath and insulating material therebetween, a terminal box into which the said inner conductor projects and in which it is bent substantially at right angles, and a terminal pin projecting into said terminal box into contact with said inner conductor. v

9. An electric resistance heating unit comprising a metallic disk, and a resistance conductor wound around the periphery thereof so that the tops of the turns lie in the same plane as the top of the disk and in good thermal relation therewith.

10. An electric resistance heating unit comprising a metallic disk and a heating element secured to the periphery thereof and having its top in substantially the same plane as the top of the disk, the heating element comprising a plurality of resistance coils secured together by spacing members of a material having good heat conductivity located between the respective coils.

11. An electric resistance heating unit comprising a flat metallic disk and a heating unit secured to the periphery thereof and having its top in substantially the same cured together to form a unit presenting a i@ plane as the top of the disk, the heating unit substantially flat top surface.

comprising a plurality of coils of metallic In witness whereof, l have hereunto sei:v sheath Wire formed of a resistance member my hand this lh day of April, 1913.

surrounded by insulation inclosed in ametal- HENRY PRICE BALL lic tube, and metallic spacing members having their edges conforming to the shape of 1Witnesses:

the lsheath wire located between the coils, the J. G. EDDY, coils, spacing members and disk being; se- M. J. REYNOLDS.y 

